/**
 * Cookie configuration helpers
 * Automatically uses secure settings in production
 */

const isProduction = process.env.NODE_ENV === 'production';

/**
 * Domain the session cookies are scoped to.
 *
 * Set `COOKIE_DOMAIN=.qrmaster.net` in production so one session is shared between
 * www.qrmaster.net (marketing, login) and app.qrmaster.net (the app). Without it the
 * cookie stays host-only and a user logged in on www would be anonymous on app.
 *
 * Only honoured in production on purpose: browsers reject dotted domains for
 * `localhost`, so a prod .env copied into a dev environment would silently break
 * every login instead of just ignoring the value.
 */
export function getCookieDomain(): string | undefined {
  if (!isProduction) {
    return undefined;
  }

  const domain = process.env.COOKIE_DOMAIN?.trim();

  return domain ? domain : undefined;
}

/**
 * Name of the session cookie.
 *
 * Configurable so a staging deployment on another qrmaster.net subdomain can pick a
 * distinct name. Production scopes its cookie to `.qrmaster.net`, so the browser sends it
 * to testmodul.qrmaster.net as well; two cookies with the same name would make
 * `cookies.get()` ambiguous and staging logins flaky.
 *
 * Like COOKIE_DOMAIN this must be set at build time too, because process.env is inlined
 * into the Edge middleware bundle.
 */
export function getAuthCookieName(): string {
  return process.env.AUTH_COOKIE_NAME?.trim() || 'userId';
}

/**
 * Get cookie options for authentication cookies
 */
export function getAuthCookieOptions() {
  return {
    httpOnly: true,
    secure: isProduction, // HTTPS only in production
    sameSite: 'lax' as const,
    path: '/', // Explicit so the expiry in buildExpiredCookieHeaders() matches
    maxAge: 60 * 60 * 24 * 7, // 7 days
    domain: getCookieDomain(),
  };
}

/**
 * Get cookie options for CSRF tokens
 * Note: httpOnly is false so the client can read it, but we verify via double-submit pattern
 */
export function getCsrfCookieOptions() {
  return {
    httpOnly: false, // Client needs to read this token for the header
    secure: isProduction, // HTTPS only in production
    sameSite: 'lax' as const,
    maxAge: 60 * 60 * 24, // 24 hours
    path: '/', // Available on all paths
    domain: getCookieDomain(),
  };
}

/**
 * Get cookie options for short-lived flow cookies (OAuth state, post-auth redirect).
 */
export function getFlowCookieOptions(maxAgeSeconds: number) {
  return {
    httpOnly: true,
    secure: isProduction,
    sameSite: 'lax' as const,
    path: '/',
    maxAge: maxAgeSeconds,
    domain: getCookieDomain(),
  };
}

function serializeExpiredCookie(name: string, httpOnly: boolean, domain?: string): string {
  const parts = [
    `${name}=`,
    'Path=/',
    'Max-Age=0',
    'Expires=Thu, 01 Jan 1970 00:00:00 GMT',
    'SameSite=Lax',
  ];

  if (domain) {
    parts.push(`Domain=${domain}`);
  }
  if (httpOnly) {
    parts.push('HttpOnly');
  }
  if (isProduction) {
    parts.push('Secure');
  }

  return parts.join('; ');
}

/**
 * Build every `Set-Cookie` value needed to actually delete a cookie.
 *
 * A cookie is only removed by a Set-Cookie whose name, path AND domain match what the
 * browser stored. Since we moved the session to a shared COOKIE_DOMAIN, a returning user
 * can hold BOTH variants at once: a host-only cookie set before the switch and a
 * domain-scoped one set after. Expiring only one leaves the other in place and the user
 * stays effectively logged in — so we always emit both.
 */
export function buildExpiredCookieHeaders(name: string, httpOnly: boolean): string[] {
  const domain = getCookieDomain();
  const headers = [serializeExpiredCookie(name, httpOnly)];

  if (domain) {
    headers.push(serializeExpiredCookie(name, httpOnly, domain));
  }

  return headers;
}

/**
 * Append expiry headers for the given cookies onto a response.
 *
 * IMPORTANT: call this AFTER the last `response.cookies.set()` on the same response.
 * Next's ResponseCookies is keyed by cookie name and rewrites the whole `set-cookie`
 * header from its internal map on every `set()`, which would drop these appends and
 * collapse our two variants back into one.
 */
export function appendExpiredCookies(
  headers: Headers,
  cookies: Array<{ name: string; httpOnly: boolean }>
): void {
  for (const cookie of cookies) {
    for (const value of buildExpiredCookieHeaders(cookie.name, cookie.httpOnly)) {
      headers.append('set-cookie', value);
    }
  }
}

/**
 * Check if running in production
 */
export function isProductionEnvironment(): boolean {
  return isProduction;
}